Preprint of "MXene modified CoZnCr for efficient water splitting from alkaline seawater and anion exchange membrane electrolyzer"

MXene-assisted CoZnCr for efficient alkaline seawater splitting and anion exchange membrane electrolyzer Payal Chauhan1*, Prosun Santra2, Bing Wu1, Jan Plutnar1, Jakub Regner1, Alkesh B. Patel1, Martin Loula3, Mahdi Ghorbani-Asl2, Arkady V. Krasheninnikov2, Saeed Ashtiani1, Bahareh Khezri4, Zdeněk Sofer1* 1Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, Prague 6, 16628 Czech Republic 2Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum DresdenRossendorf, 01328 Dresden, Germany. 3Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic 4Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel. lí Domingo 1, Tarragona 43007, Spain Corresponding Authors: Payal Chauhan, Email: cha[email protected] Zdenek Sofer, Email: sofer[email protected] Abstract: Designing efficient electrocatalysts for industrial-scale seawater splitting that can mitigate anodic corrosion while effectively driving oxygen evolution remains a significant challenge. Strategic surface engineering is crucial in developing electrocatalysts, bridging the gap between fundamental research and the practical demands of industrial water-splitting applications. In this work, we present the development of a CoZnCr@MXene heterostructure, which achieves a low cell voltage of 1.55 V at a current density of 50 mA cm⁻² and outperform RuO₂ in alkaline seawater electrolyte. The remarkable performance is attributed to synergistic enhancements arising from compositional tuning, surface engineering, and the integration of conductive supports, which collectively lead to substantial reductions in overpotentials for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The CoZnCr@MXene catalyst exhibits excellent stability and selective oxidation in alkaline seawater, with MXene incorporation effectively suppresses chloride-induced corrosion while enhancing charge transfer efficiency. Furthermore, when employed in an anion exchange membrane (AEM) electrolyzer, the CoZnCr@MXene catalyst delivers a current density of 500 mA cm⁻² at an operating voltage of 1.72 V at 60 °C, corresponding to a cell efficiency of 77.8%. The calculated hydrogen production cost is $0.86 per gallon of gasoline-equivalent (GGE), significantly below the 2026 technical target of $2.00/GGE set by the U.S. Department of Energy. This work represents a significant breakthrough in the design of long-lasting, noble-metal-free electrodes for industrial-scale alkaline seawater electrolysis. Introduction: As a sustainable energy source, hydrogen has the potential to reduce greenhouse gas emissions from conventional fossil fuels and their negative effects on the environment. Water electrolysis is the most appropriate approach to generate high-purity hydrogen production since it can efficiently utilize solar and wind energy.1,2 So far, high-purity water remains the primary raw material for commercial electrocatalytic hydrogen generation. However, the global shortage of freshwater resources (approximately 3% of earth's water) demands the development of catalytic electrodes based on abundant metal elements for electrolysis of non-drinkable water sources.3 Seawater splitting is a prominent alternative as it makes up about 96.5% of the world's total water.4 One of the main advantages is that seawater, which makes up more than 70% of the Earth's surface, is readily available and offers an almost infinite supply of feedstock for electrolysis, allaying worries about freshwater shortages. It offers many benefits, such as the ability to produce green hydrogen, reduced competition with fresh water, and the utilization of a plentiful and renewable resource. With the added advantages of affordability, environmental sustainability, and scalability, seawater electrolysis offers a very promising way to meet the world's energy needs and help us move toward a sustainable, hydrogen-powered future.5 However, the dissolved ions in seawater, particularly chloride ions block the catalytic active sites and reduce the durability and efficiency of seawater splitting.6 The long-term stability and cost-effectiveness of seawater electrolysis systems are significantly hampered by corrosion, particularly when subjected to a harsh, salty environment for long periods. Although various current studies have focused on freshwater electrolysis, alkaline saltwater electrolysis is becoming more and more acknowledged as a practical and beneficial substitute, particularly considering the large and plentiful supply of seawater.7 Alkaline seawater electrolysis has emerged as a preferred method for seawater splitting, as it eliminates the need for a continuous alkali supply and effectively mitigates the anodic chloride oxidation reaction (COR). 8,9 Recently, many researchers have focused on an anion exchange membrane (AEM) as the separator for seawater electrolysis. However, chloride ions (Cl⁻) still appear to pass through the membrane towards the anode under the applied electric field. This results in the unwanted chloride oxidation reaction (ClOR) at the anode, which can cause degradation of the membrane. Therefore, it is essential to develop OER catalysts that have excellent salt tolerance in order to enhance the advancement of large-scale seawater electrolysis. Lately, significant reports have been published on low-cost transition metal catalysts such as NiS10, MoS211 and P-CoNiO212 for water splitting in an alkaline medium. Most of the catalysts are not suitable for industrial conditions due to the harsh conditions (60-80 °C, 400 mA cm−2), bubble desorption and less occupancy of hydrogen bubbles at the active sites on the surface of electrocatalyst due to the inappropriate Gibbs-free energy.13 To withstand extreme working conditions, industrial electrocatalysts must fulfil specific requirements such as low-cost materials with fast synthesis routes, active catalyst sites, suitable Gibbs-free energy and excellent chemical and structure stability. 14,15,16 Layered double hydroxides (LDH) are the most promising candidates to match the above criteria as they exhibit high OER electrocatalysis.17 The unique structural design exposes the catalyst's active sites and enhances the electrochemical surface area of the OER electrocatalyst.18 For example, Fe, Co, Ni, Zn, and Mn-based LDHs have been studied widely for OER.19, 20, 21 Y. Gong et. al reported FeCo LDH for seawater electrocatalyst using a surface corrosion method, achieving the overpotential of 229 mV at a current density of 100 mA cm-2.22 Y. Park et. al concluded that NiFeCo LDH based AEM alkaline seawater electrolyzer with potential less than 1.72 V can completely suppress the chloride evolution reaction (ClER) thermodynamically.23 Therefore, developing efficient and durable electrocatalysts that allow for direct seawater electrolysis at low voltage is very desirable. In this study, we present a highly efficient and stable CoZnCr@Mo2TiC2 alkaline seawater electrocatalyst. The electrocatalyst has a high durability with a stable long-term performance in alkaline media with a low overpotential of 45 mV at 10 mA cm-2 for HER, which is quite lower than that of Pt/C catalyst (58 mV). Similarly, the catalyst provided low overpotential of 47 mV at 50 mA cm-2 for OER surpassing RuO2 (93 mV). It required the cell voltage of 1.54 V and 1.62 V to reach current densities of 100 mA cm-2 and 200 mA cm-2 in an alkaline medium. In addition, the AEM alkaline seawater cell needs a cell voltage of 1.73 V to reach a current density of 0.6 A cm-2, performing the state-of-the-art electrolyzer for seawater electrocatalysis. An AEM electrolyzer catalyzed by CoZnCr@Mo2TiC2 electrocatalyst is stable over more than 17 days with a faradic efficiency of 100 %. The price of hydrogen (H2) produced per gallon of gasolineequivalent (GGE) is $0.89, which is below the U.S. Department of Energy's (DOE) target of $2.00 per GGE by 2026, suggesting superior application prospects. This work provides an optimal approach towards developing a highly efficient, corrosion and stable industrial scale catalyst at low potential for seawater electrocatalyst. It delivers a deeper understanding of the factors driving performance enhancement and offers valuable insights for the design of future catalysts. Methods: Chemicals: Cobalt nitrate hexahydrate (Co(NO3)2·6H2O), zinc nitrate hexahydrate (Zn(NO3)2·6H2O), chromium nitrate hexahydrate (Cr(NO3)3·9H2O), 2-methylimidazole (C4H6N2, 2-MIM), ruthenium (IV) oxide (RuO2) and urea (NH2CONH2) were supplied by Lachema. Mo2TiAlC2, potassium hydroxide (KOH, Sigma SigmaAldrich, 99.99%), Pt/C (20 wt% Pt), sodium chloride (NaCl), Nafion (5 wt% Nafion polymer is dissolved in a combination of lower aliphatic alcohols and water), methanol (CH3OH), ethanol (C2H5OH) and hydrochloric acid (HCl) were purchased from Fluorochem. Nickel foam was obtained from Sigma-Aldrich. Preparation of ZIF-67 Co(NO3)2 (894 mg) was dissolved in methanol (5 mL) and stirred for 10 min. 2-MIM (985 mg) was dissolved in methanol (30 mL) and stirred at room temperature for 10 min. Then, both solutions were mixed together and stirred at room temperature for 24 hr. The product was collected by centrifugation followed by repeated washings with ethanol and dried at 60 °C overnight. Preparation of CoZnCr LDH: The CoZnCr LDH was prepared using a hydrothermal method. Briefly, Zn(NO3)2·6H2O (150 mg), Cr(NO3)3·9H2O (50 mg) and urea (9 mg) were dissolved in ethanol (60 mL) and stirred for 5 min. ZIF-67 powder (50 mg) was added to the solution and stirred for 20 min. The mixture was transferred into a Teflon liner loaded in an autoclave and heated to 120 °C for 6 h. After cooling down to room temperature, the product was isolated by centrifugation using water and ethanol as dispersing media and dried at 60 °C overnight. Preparation of LDH@Mo2TiC2 MXene: For the preparation of LDH@Mo2TiC2, CoZnCr LDH (12 mg) was added to deionized water (10 mL), and stirred for 10 min. In another beaker, Mo2TiC2 MXene (1 mg) was added to deionized water (10 mL) and stirred for 10 min. Then, both solutions were mixed and stirred for 20 min. The solution was then centrifuged at 1000 rpm for 15 min. The product was collected and dried at 60 °C overnight. Material characterization: The structural and chemical analyses were performed by powder X-ray diffraction (XRD) (Bruker D8, Cu X-ray source, λ = 0.15418 nm) and X-ray photoelectron spectroscopy (XPS) (SPECS spectrometer equipped with a monochromatic Al Kα X-ray source (1486.7 eV) and a hemispherical electron analyzer Phoibos 150). The morphology and composition of synthesized materials were examined using SEM/STEM (Tescan MAIA 3, Czech Republic) and HRTEM (JEOL 2200 FS, Japan). The detailed structural characterizations were examined using the transmission electron microscope (TEM) (JEOL 2200 FS (Japan)). The bubble contact angles were analyzed via ADVEX Instruments, Czech Republic Electrochemical measurements: Electrochemical measurements were performed using a potentiostat (Metrohm) with a three-electrode electrochemical system in a laboratory at room temperature. As for the preparation of the working electrode, the catalyst powder (LDH@MXene, 3 mg) was mixed with Nafion solution (40 µL) and ethanol-water mixture (200 µL/100 µL), followed by sonication for 20 min to make an ink like solution and then dropped cast on Nickel foam (1×1 cm active area) and dried at ~60 °C. For the preparation of Pt/C (40% Pt/C) and RuO2 (3mg RuO2), the same procedure was followed. The as-prepared electrode, Hg/HgO (1M KOH) and graphite rod were used as a working, reference and counter electrode for HER analysis respectively. For the OER measurements, platinum was used as a counter electrode. All potentials were converted to reversible hydrogen electrode (RHE) using the Nernst equation (𝐸𝑅𝐻𝐸 = 𝐸𝐻𝑔⋰𝐻𝑔𝑂 + 0.0591 + 0.098 × 𝑝𝐻).24 Before analysis, the sample was scanned with 20 cycles of cyclic voltammetry (CV) to reach stabilization. The linear sweep voltammetry (LSV) for HER and OER were recorded with the sweep rate of 10 mV s-1 under various electrolyte solutions (1M KOH, 1M KOH+NaCl (0M to sat. NaCl), 1M KOH+seawater, Natural Seawater). For comparison, linear sweep voltammetry of 40% Pt/C (for HER) and RuO2 (For OER) were measured under 1M KOH. The Tafel slop was calculated from LSV using Tafel equation ɳ = 𝑏𝑙𝑜𝑔(𝑗 𝑗0 ⁄ ),25 where ɳ is overpotential, b is Tafel slop, j is current density and j0 is exchange current density. The electrochemical impedance spectroscopy (EIS) was obtained at a frequency range from 0.1 Hz and 100 kHz with an amplitude of 10 mV. The durability was measured at a constant current density of 100 mA cm-2 for 150 hr in three-electrode. The double-layer capacitance (Cdl) of the electrode was evaluated using cyclic voltammetry at different scan rates ranging from 10 mV s-1 to 100 mV s-1. The sample names free-standing LDH and supported LDH indicate the CoZnCr and CoZnCr@Mo2TiC2 respectively. AEM electrolyzer fabrication: The AEM electrolyzer was assembled using an anode (2.2 cm²), a cathode (2.2 cm²), and an anion exchange membrane. Both the anode and cathode were fabricated on nickel foam (2.2 × 2.2 cm-2) by directly depositing CoZnCr@Mo₂TiC₂ catalyst at a loading of 4 mg cm⁻², forming a CoZnCr@Mo₂TiC₂||CoZnCr@Mo₂TiC₂ AEM electrolyzer. For comparison, a RuO₂||Pt/C electrolyzer was prepared by depositing RuO₂ (4 mg cm⁻²) onto nickel foam as the anode, while the cathode was prepared by applying Pt/C with Nafion onto nickel foam using the same method as the anode. The electrochemical performance of the AEM electrolyzer was evaluated using 1 M KOH and a 1 M KOH + seawater electrolyte, which was introduced into the AEM cell via a peristaltic pump at both room temperature and 60 °C. Linear sweep voltammetry (LSV) was performed at a scan rate of 10 mV s⁻¹. The long-term stability of the electrolyzer was measured via chronopotentiometry at a constant current density of 500 mA cm⁻² over 410 hr. The internal cell temperature was maintained at 60 °C by continuously circulating a preheated electrolyte (60 °C) through the system. Faradaic efficiency (FE) was determined using the drainage method at a constant current density of 500 mA cm⁻² in 1 M KOH + seawater. Results and discussion: Preparation and characterization of the CoZnCr LDH@Mo2TiC2 MXene We used the self-assembly method to synthesize CoZnCr@Mo2TiC2, as presented in Fig. 1 (see methods for detail). The scanning electron microscopy revealed a well-defined dodecahedral morphology (Fig. 2a).26 Upon transformation of ZIF-67 into CoZnCr LDH, the initially smooth surface evolved into a nanosheetclustered structure, as shown in Fig. 2b.27 The incorporation of Mo₂TiC₂ MXene into CoZnCr-LDH preserved the nanosphere-like architecture of LDH while introducing nanoparticle-wrapped surfaces Fig. 2c. Fig. 1 Schematic illustration of the synthesis process of CoZnCr@MXene. To further investigate, the structural and compositional characteristics, scanning transmission electron microscopy (STEM) was employed, confirming the retention of the dodecahedral shape in CoZnCr@Mo₂TiC₂, as shown in Fig. 2d. Elemental mapping of Co, Zn, Cr, Mo, Ti, and C demonstrated a uniform distribution of elements throughout the composite (Fig. 2e). High-resolution transmission electron microscopy (HRTEM) revealed the presence of a distinct hollow nanocage structure, shown in Fig. 2f, g, in agreement with the SEM observations. The presence of hollow cavities within CoZnCr@Mo₂TiC₂ serves as an electrolyte reservoir, enhancing the contact between electrolyte ions and the material, thereby facilitating electrochemical reactions.28 The selected area electron diffraction (SAED) pattern (inset, Fig. 2g) further confirms the crystallinity of the synthesized composite. Fig. 2h, i depict well-resolved lattice fringes with interplanar spacing of 0.25 nm and 1.12 nm, corresponding to the (012) and (002) planes of LDH and MXene, respectively, which is further confirmed by the XRD29. The XRD pattern of CoZnCr@Mo₂TiC₂ aligns with the characteristic peaks of both Mo₂TiC₂ and CoZnCr, as presented in Supplementary Fig. 1a, b. Notably, the diffraction peaks at 31.7° and 36.2° correspond to the (012) and (015) planes of CoZnCr, while the peak at 7.3° is indexed to the (002) plane of Mo₂TiC₂, consistent with the HRTEM results. The chemical state of CoZnCr@Mo2TiC2 was investigated using X-ray photoelectron spectroscopy (XPS). The Zn 2p spectrum exhibits two distinct peaks at 1023.6 eV and 1046.6 eV, corresponding to Zn 2p3/2 and Zn 2p1/2, respectively, indicating the presence of Zn²⁺ (Supplementary Fig. 2a). Similarly, the Cr 2p spectrum displays peaks at 579.4 eV and 589.1 eV, attributed to Cr 2p3/2 and Cr 2p1/2, respectively (Supplementary Fig. 2b), confirming the oxidation state of Cr in the composite. Fig 2. SEM image of as prepared a ZIF-67. b CoZnCr. c CoZnCr@Mo2TiC2. d STEM image of as prepared CoZnCr@Mo2TiC2. e elemental mapping showing the uniform distribution of Co, Zn, Cr, Mo, TI and C. f, g HRTEM image of CoZnCr@Mo2TiC2. h, i Lattice fringes of CoZnCr and Mo2TiC2. The deconvolution of the high-resolution spectrum of the Mo 3d region suggests the presence of Mo in two oxidation states, Mo4+ and Mo6+, respectively. The peaks at 231.0 and 234.2 eV correspond to the 3d5/2 and 3d3/2 components of Mo4+, respectively, and the peaks at 234.7 and 237.7 eV correspond to the same components of Mo6+ Supplementary Fig. 2c.29, 30 The XPS C 1s spectrum reveals peaks at 286.9 eV, 285.7 eV, and 282.2 eV, which are assigned to C–O, C–C, and Mo(Ti)–C bonds, respectively (Supplementary Fig. 2d). Additionally, the O 1s spectrum displays peaks at 532.4 eV and 534.0 eV, corresponding to Mo– OH and O–C species, respectively, as shown in Supplementary Fig. 2e. Electrocatalyst for alkaline electrolysis Half-cell performance of CoZnCr@Mo2TiC2 electrode The electrochemical performance of the CoZnCr@Mo₂TiC₂ electrode was evaluated using half-cell water electrolysis in a 1.0 M KOH electrolyte. Fig 3. Electrochemical performance. a. HER polarization curves of CoZnCr@MXene, CoZnCr, ZIF-67, Pt/c and Ni foam in 1M KOH. b. Tafel slopes of the five electrocatalysts-HER. c. OER polarization curves of CoZnCr@MXene, CoZnCr, ZIF-67, RuO2 and Ni foam in 1M KOH. d. Tafel slopes of the five electrocatalysts-OER. e. comparative overpotential of three different electroctalyst at various current densities. f. Polarization curves of overall water splitting (OWS) in 1M KOH. g. i. Contact angles (staticwater-droplet) for CoZnCr@MXene and Ni foam. ii. Digital photos demonstrate the hydrogen release behavior. h. Long-term stability test at 100 mA cm-2. electrical conductivity, allowing for efficient electron transfer in electrocatalysis. To determine the most favourable surface-active site for each intermediate step, we compared the adsorption energies across different surface sites. In the case of HER (Fig. 6b), the Gibbs free energy values of the key intermediates (*H) on freestanding LDH are positive, with a minimum barrier of 0.4 eV. It is evident that the presence of MXene significantly influences the HER energy barrier of heterostructure compared to the freestanding CoZnCr (see Table S7). The CoZnCr@Mo2TiC2(OH)2 exhibits the lowest energy barrier among the different considered surface terminations, suggesting high catalytic activity for HER. Moreover, the free energy of hydrogen adsorption (ΔGH*) is a key parameter influencing HER performance, with a value close to zero suggesting optimal H adsorption and efficient H2 release. The calculated ΔGH* value for CoZnCr@ Mo2TiC2 is 0.06 eV, which is nearer to the thermoneutral point compared to the values for CoZnCr (0.39 eV) (Fig. 6c) indicating a surface that facilitates the efficient desorption of the evolved hydrogen species. Notably, hybridization is more pronounced in the case of CoZnCr and Mo₂TiC₂O₂, resulting in the highest charge transfer and interfacial binding energies, as shown in Fig. 6d and Table S8. This strong interaction effectively lowers the energy barrier for *OOH formation, the rate-limiting step, further improving OER efficiency. The structural configurations of intermediates (Fig. 6e) reveal that Cr atoms serve as the most favourable adsorption sites for stabilizing intermediates during the OER process. Free energy profile calculations (Fig. 6f) indicate that the rate-limiting step in supported heterostructures corresponds to the transformation of [O*] to [*OOH], consistent with a previous report 39. However, the overpotential is lower than that of freestanding LDH under similar conditions, suggesting faster OER kinetics on CoZnCr@Mo₂TiC₂. Thus, the incorporation of Mo₂TiC₂ modifies the Gibbs free energy landscape of the HER-OER pathway and tunes the electronic structure of the catalyst resulting in enhanced HER and OER activity. Performance of an AEM seawater electrolyzer We further assembled an alkaline seawater AEM electrolyzer utilizing CoZnCr@MXene as both the anode and cathode, as depicted in Fig. 7a. The polarization curve for overall water splitting in 1 M KOH + seawater reveals that the electrolyzer requires a cell voltage of 1.64 V to achieve a current density of 100 mA cm⁻² at 26°C, which is significantly lower than the commercial Pt/C||RuO₂ electrolyzer (1.77 V) under the same current density, as shown in Fig. 7b. This demonstrates that the CoZnCr@MXene-based AEM electrolyzer outperforms commercial electrocatalysts in terms of efficiency. Additionally, using a drainage gas collection method, the O₂ gas production from the CoZnCr@MXene electrolyzer was measured (Supplementary Fig. 11a, b), yielding a Faradaic efficiency of 99% in alkaline seawater electrolyte, as shown in Fig. 7c. The catalyst also exhibited exceptional durability, maintaining a stable performance at a current density of 200 mA cm⁻² for 16.8 days, with negligible cell voltage degradation, indicating outstanding stability and high selectivity for alkaline seawater electrolysis, as demonstrated in Fig. 7d. Furthermore, the CoZnCr@MXene||CoZnCr@MXene-catalyzed AEM electrolyzer exhibits a cell efficiency of 77.8%, surpassing the U.S. Department of Energy (DOE) target efficiency of 77%, at a current density of 0.2 A cm⁻² (Supplementary Fig. 11c and Supplementary Note 1). Additionally, a critical metric of the electrolyzer’s economic viability is the hydrogen production cost, which is calculated to be as low as $0.86 per GGE of H₂, as detailed in Supplementary Note 1. Fig 7. AEM electrolyzer performance in alkaline seawater. a. Schematic illustration of AEM electrolyzer. b. Polarization curves of CoZnCr@MXene|| CoZnCr@MXene in 1M KOH+seawater at 26 °C and 60 °C with Pt/C||RuO2. c. FE ofproducing O2. d. Durability test of the CoZnCr@MXene|| CoZnCr@MXene AEM electrolyzer in 1M KOH+Seawater electrolyte at 200 mA cm-2. This value is less than half of the DOE’s 2026 target of $2.00 per GGE, demonstrating the potential for economical hydrogen production.40 These results highlight a promising pathway for the efficient and costeffective production of H₂ and O₂ via seawater electrolysis, facilitated by outstanding catalytic activity and stability. This remarkable performance can be attributed to: (1) the unique nanocage architecture, which facilitates optimal interface interaction and creates a high density of active catalytic sites; (2) the synergistic interplay between the catalyst’s hierarchical structure and compositional attributes, which enhances the interfacial electron transfer between active sites and the substrate, thereby significantly improving the intrinsic catalytic activity; and (3) the chloride ion resistance of CoZnCr@MXene, which minimizes Cl⁻ interference, promotes the H₂O-OH⁻ reaction pathway, and ensures selective catalysis. Conflict of Interests There are no conflicts to declare. Conclusion: In summary, we successfully developed a CoZnCr@MXene electrocatalyst for selective, efficient and highly stable alkaline seawater electrolysis at higher current densities. The hierarchical hollow structures enhance the diffusion of reactants and products to and from the catalytic sites. Increasing the number of such sites lowers the overall activation energy; and promotes efficient electron transfer, facilitating faster charge transfer and reaction kinetics. The catalyst displays a good HER and OER performance with a low overpotential of 45 mV and 20 mV at 10 mA cm-2 in an alkaline medium respectively. Notably, the catalyst exhibits an impressive performance, with an overpotential increase of less than 63 mV as the salt concentration in the electrolyte increases from 0 M to saturated NaCl. Moreover, CoZnCr@MXene exhibits a low cell voltage of 1.60 V at 100 mA cm-2 current density in alkaline seawater electrolyte higher stability for electrocatalytic seawater OER. The CoZnCr@MXene AEM seawater electrolyzer achieves high performance with a cell voltage of 1.83 V at 1000 mA cm-2 at industrial conditions with high cell efficiency of 77.8 % and durability over 16.8 days (0.2 A cm-2) in alkaline seawater electrolyte. Moreover, the DFT calculations revealed that MXene plays a crucial role in enhancing HER and OER performance by significantly improving electroactivity, strengthening adsorbate binding, and facilitating efficient electron transfer. The result outperforms reported articles in seawater electrolysis. The results provide important insights for effective electrolyzer design and a strategic approach to catalyst development for seawater electrolysis with low energy consumption. Data Statement: The datasets generated during and/or analyzed during the study are accessible via the Zenodo repository: https://doi.org/10.5281/zenodo.15100523 Acknowledgements P.C. acknowledges the financial support from the European Union's Horizon Europe research and innovation program under the Marie Skłodowska - Curie grant agreement No. 101130803. AVK acknowledges funding from the German Research Foundation (DFG), project KR 4866/9-1 and the collaborative research center “Chemistry of Synthetic 2D Materials” CRC-1415-417590517. Generous CPU time grants from the Technical University of Dresden computing cluster (TAURUS) and Gauss Centre for Supercomputing e.V. (www.gauss-centre.eu), Supercomputer HAWK at Höchstleistungsrechenzentrum Stuttgart (www.hlrs.de), are greatly appreciated. This work was supported by the project “The Energy Conversion and Storage“ funded as project No. CZ.02.01.01/00/22_008/0004617 by Programme Johannes Amos Commenius, call Excellent Research. References: 1. Han, X. et al. Ultrafine Pt Nanoparticle-Decorated Pyrite-Type CoS2 Nanosheet Arrays Coated on Carbon Cloth as a Bifunctional Electrode for Overall Water Splitting. Adv. Energy Mater. 8, 1–12 (2018). 2. Liu, P. et al. Tip-Enhanced Electric Field: A New Mechanism Promoting Mass Transfer in Oxygen Evolution Reactions. Adv. Mater. 33, 1–9 (2021). 3. 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